Flame resistant aromatic carbonate polymers are well known. Alkali metal salts of sulfonated compounds, particularly sulfonated aromatic compounds are particularly effective as flame retardant additives for aromatic carbonate polymers. These compounds, used in additive quantities, provide an aromatic carbonate polymer composition which is resistant to flammability, and can pass various Underwriter Laboratory test levels. Thus the usage of aromatic carbonate polymers has been expanded into areas where increased flame resistance is a requirement. However, because the compounds are employed as additives rather than incorporated into the actual polymer, several problems have occurred. The optical clarity of the resin, as measured by haze and transmission of light, has at times suffered somewhat from the addition of the additive quantities of a sulfonate salt.
The incorporation of the critical flame retardant functionality into the polymer itself should provide the physical compatibility necessary to overcome any optical clarity problem. Such incorporation has now been accomplished with the concurrent elimination of a separate end-capping agent. The moiety which provides flame resistance to the aromatic carbonate polymer has the dual function of end-capping the polymer as well.